How will iPhone 6's Wi-Fi calling, VoLTE affect enterprise networks?

While the cosmetic features like screen size and processing power of Apple's new iPhone 6 and 6 Plus attracted the most attention, their use of Wi-Fi and Voice over LTE (VoLTE) for voice and video calling could eventually have a major impact on how phone calls are handled in the enterprise.

On its website, Apple touts the iPhone's Wi-Fi voice and video calling feature as a good solution "when you don't have a good cellular signal." As this helpful Gizmodo guide to Wi-Fi calling points out, Wi-Fi calling could help users save money by using an internet connection instead of a carrier's network, and unlike other services like Skype and Google Voice, users can make and receive calls with the same phone number they use for traditional phone calls. This makes it helpful for employees visiting clients' offices or attending large events, relying on the available Wi-Fi networks to make calls and send text messages without running up their wireless bills.

In order for Wi-Fi calling to be truly useful, the device using it will need to be able to transition on and off Wi-Fi networks without dropping the call. That's why Apple's website discusses the iPhone's Wi-Fi calling in the context of VoLTE, which many consider the only option for a seamless transition between Wi-Fi and carriers' networks. As Gizmodo pointed out, T-Mobile offers Wi-Fi calling not only on the iPhone but also on several Android and Windows Phone smartphones, but warns in fine print that "most devices will not transition between Wi-Fi and the wireless network."

This is the catch -- it might be a while before iPhone users (and their Android counterparts) can really make use of Wi-Fi calling and VoLTE because it might be a while until carriers support both. T-Mobile currently supports Wi-Fi calling but not VoLTE, hence the disclaimer. Ditto for Sprint, which does not yet offer Wi-Fi calling for the iPhone but does for some Android devices. Verizon Wireless announced its VoLTE voice and video calling service this week, but the company "said it had no plans for Wi-Fi calling," according to a recent CNET report. AT&T appears to have hit the nail on the head, downplaying T-Mobile's Wi-Fi calling win with the iPhone (it was the only provider shown at Apple's iPhone announcement event that supports the feature) and announcing that it will roll out VoLTE soon and Wi-Fi calling in 2015.

Even when the carriers do support VoLTE, it might not be as useful as advertised. Verizon Wireless is already advertising its VoLTE service, called Advanced Calling 1.0, but warns that "HD Voice requires both parties to use a Verizon HD Voice-enabled phone on Verizon's 4G LTE network." So that transition from Wi-Fi calling to VoLTE will only be seamless when calling another Verizon user.

Pricing is likely to differ among carriers, but Verizon Wireless is offering its Advanced Calling service at no additional charge and says voice calls made over VoLTE will be billed no differently than traditional voice calls (video calls, however, will count toward users' monthly data allotment). So the benefit of VoLTE, at least from a financial standpoint, is the ability to transition off VoLTE networks and onto Wi-Fi networks, which could reduce monthly wireless costs for voice and messaging.

Some may eventually considering adopting Wi-Fi calling as a voice plan for in-office phone calls. This isn't necessarily a bad idea -- more and more people are replacing their home landline phones with cellphones, so why shouldn't they do the same at the office? Employees will only need to list one phone number on their business cards and will only receive voicemails on one device. Dropped calls for carriers that don't use VoLTE won't be an issue for employees who are taking calls at their desks, where they aren't likely to wander out of range of the office's Wi-Fi network.

To do so, the bandwidth that these Wi-Fi calls consume would have to be taken into consideration. Estimates vary on the bandwidth impact of Wi-Fi calling. Republic Wireless, a wireless provider that pushes Wi-Fi calling as the primary connection, says in its FAQ that "you need about 80kbps both ways to hold a call." T-Mobile's fine print lists standard speeds at "approx. 128 Kbps." And an article at The Verge says "a typical voice call tops out at around 12kbps, but can scale as low as 4.75kbps when the going gets rough -- silence is transmitted over GSM at a rate of 1800 bits per second."

"'Oh, but what about HD voice calls, the future of phone calling?' you say," The Verge article continued. "Bump the bitrate to... 12kbps. That's what the AMR-WB (Adaptive Multi-Rate Wideband) codec calls for. Maybe 30 or 40kbps if you want to add in some background noise cancellation and stereo audio. Older, less efficient codecs (often in use by VoIP services) hover around 60kbps. Even Skype's vaunted voice codec tops off at 40kbps, going as low as 6kbps for low-end devices. There's so much room left over for 1080p YouTube streaming, trust me."

As broadband speeds continue to improve and Wi-Fi becomes available on more high-end smartphones, Wi-Fi calling has the potential to become the new de facto voice option in the workplace.

Apple's new Wi-Fi calling and VoLTE features aren't new, and they aren't likely to spur any change overnight. However, they could be a sign of things to come.

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